You need the original, unmodified Japanese ISO of Shin Sangokumusou 5 Special (ULJM-05522 or ULJM-05559, depending on the edition).

While Dynasty Warriors 6 was a hit in Japan, its lack of English support made it inaccessible to many fans worldwide. The game's Japanese text and audio presented a significant barrier to entry, making it difficult for non-Japanese speakers to fully appreciate the game's story, characters, and gameplay.

Why hasn't a patch been made? Fan translation is an immense amount of work, requiring volunteers to extract, translate, and re-insert hundreds of thousands of lines of text. For a niche title that was already less popular than its PS3 counterpart, the community support required simply never materialized.

: For those playing on an emulator, the most comprehensive "English" experience is often achieved through HD texture packs